CONCHII'ERA. 
437 
surface of the beaks j lower valve, with a notch near the poste¬ 
rior margin. 
Pedum spondyloideum. — The Spondylus-Shaped Pedum. 
Plate LXXXVIII. fig. 9. 
Ovate, wedge-shaped, Hat; the superior valve with longitu¬ 
dinal striae, white, granulated and rough, slightly tinged with 
purple near the beak. Two inches and a half long. Inhabits 
the Indian ocean. 
Section III.—Ligament marginal and elongated. 
TRIBE I.-MALLEACEA. 
With foliaceous shells, more or less inequivalve ; having the 
ligament marginal, partly linear, and either simple or interrupted 
by crenulations. 
Genus 22.—M E L E A G RIN A.— Lamarck. 
Generic Character. — Somewhat equivalve, rounded and scaly 
on the outside: a sinus at the posterior side of the shell for the 
passage of the byssus, at which place the left valve is notched 
and narrow; hinge linear, and destitute of teeth; ligament 
marginal, elongated, and subexternal and dilated in the centre. 
Melecigrina margaritifera .— The Pearl-Bearing Meleagrina. 
Plate LXXXVIII. fig. 10. 
Somewhat square, compressed; undulated, and transversely 
striated, with a series of lamellated longitudinal scales ; green¬ 
ish on the outside and pearlaceous within. Ten or twelve 
inches long. Inhabits the Indian ocean. 
Genus 23.—A VICUL A.— Lamarck. 
Generic Character. —Shell inequivalve, fragile, with the top 
straight, transverse, and produced at both extremities, the ante¬ 
rior of which is caudiform; valves oblique ; the left one emar- 
ginate ; hinge linear, with one tooth in each valve, under the 
beaks ; ligament linear and marginal, placed in a long narrow 
groove. 
2 n 3 
